High-strength atmosphere corrosion resistant plate steel

ABSTRACT

High-strength atmospheric corrosion resistant plate steel is weldable under all conditions and has the following weight per cent composition: C0.03 - 0.15 Ni0.50 - 1.50 Mn1.0 - 1.9 Si0.05 - 1.0 Cu1.0 - 3.0 Al0.10 - 0.20 Nb0.01 - 0.30 N0.01 - 0.04 Pb0.05 - 0.50 Cd0.01 0.20, BALANCE ESSENTIALLY IRON.

United States Patent 11 1 Giflo et al.

[ Oct. 15, 1974 HIGH-STRENGTH ATMOSPHERE CORROSION RESISTANT PLATE STEEL [75] Inventors: Henrik Giflo; Sandor Enekes; Pal

Zambo; Jozsef Vamosi, all of Miskolc, Hungary [30] Foreign Application Priority Data May 23, 1972 Hungary LE 656 [52] US. Cl. 75/124, 75/125, 75/123 F [51] Int. Cl C22c 37/10, C22c 39/54 [58] Field of Search 75/124, 125

[56] References Cited UNITED STATES PATENTS 1/1953 Binder 75/124 3/1954 Phillips ..75/124 2,679,454 3/1954 Offenhauer 75/124 3,326,675 6/1967 Kenneford 75/124 3,403,060 9/1968 [to 75/124 Primary Examiner-Hyland Bizot Attorney, Agent, or FirmYoung and Thompson [57] ABSTRACT High-strength atmospheric corrosion resistant plate steel is weldable under all conditions and has the following weight per cent composition:

C 0.03 0.15 Ni 0.50 1.50 Mn 1.0 1.9 Si 0.05 1.0 Cu 1.0 3.0 A1 0.10 0.20 Nb 0.01 0.30 N 0.01 0.04 Pb 0.05 0.50 Cd 0.01 0.20

balance essentially iron.

1 Claim, No Drawings HIGH-STRENGTH ATMOSPHERE CORROSION RESISTANT PLATE STEEL The invention relates to a high-strength, atmosphere corrosion resistant, unconditionally weldable plate steel suitable especially for being used in the building industry, vehicle industry and mechanical industry.

Even now, corrosion resistant structural plate steel having good mechanical properties and weldable under suitable conditions are known, such as the plate steel Corten developed in the United States, the mechanical properties of which are characterized by a tensile strength of 40 60 kp. per sq. mm. and a yield point of 30 50 kp. per sq. mm. There are known steels the tensile strength of which is 50 70 kp. per sq. mm. and the yield point is between 30 and 50 kp. per sq. mm.

The present invention aims at the development of an atmosphere corrosion resistant steel weldable under whatever conditions and having higher yield point than the steels known up to now, which can be used as basic material of constructions, machines and buildings subject to the vicissitudes of weather.

The invention attains its object by that the steel according to the invention contains in addition to the iron and the usual contaminations 0.03 0.15 weight per cent of carbon, 0.05 1.0 Si, 1.0 1.9 Mn, 1.0 3.0 Cu, 0.50 1.50 Ni, 0.10 0.20 Al, 0.01 0.30 Nb, 0.01 0.04 N, 0.01 0.20 Cd. Some of these alloying elements being in a quantity corresponding to the composition ratio do not dissolve in the solid iron, moreover, they reduce the solution of elements otherwise soluble in the iron. As a consequence thereof a dense protective layer difficultly soluble under the effect of the himidity forms on the steel surface under the effect of the atmosphere, this layer protecting the steel agains the further atmosphere corrosion and precluding the possibility of pitting.

The composition of steel according to the invention provides for excellent mechanical properties and unconditional weldability, with the simultaneous suitable atmosphere corrosion resistance. The increase of values of mechanical properties is ensured by the grain refining occurring under the effect of nitrides formed in steel, by the precipitation hardening of Cu and Nb, by the interstitial incorporation of NbCN in the lattice, as well as by the anchorage of the numerous developed dislocations.

The corrosion velocity of the steel according to the invention is reduced to an extraordinary extent by the combined effect of Cu, Ni, Cb, Pb under industrial atmospheric conditions.

The steel according to the invention can be unconditionally welded; the measuring number of the C equivalent, C, is less than 0.40.

The steel according to the invention, its mechanical, weldability and corrosion properties are described by the following exemplified embodilemts.

Example 1 Tensile strength Yield point 100.0 kp. per sq.

105.8 kp. per sq.

106.0 kp. per sq.

Elongation referred to the fivefold of the diameter:

It is characteristic of its corrosion property that the corrosion velocity referred to one year results in a pen etration depth of 0.01 mm. in industrial atmosphere. It is characteristic of its weldability that the extent of hard-facing in the zone of welding heat effect has no importance at all.

It may be thus seen that the plate steel according to the invention is considerably better than the corrosion resistant steels known at present taking into account the strength properties, the corrosion properties and the weldability.

What we claim is:

l. High-strength, atmosphere corrosion resistant plate steel weldable under whatever conditions, consisting of 0.03 0.15 weight per cent of C, 0.50 1.50 weight per cent of Ni, 1.0 1.9 weight per cent of Mn, 0.05-1.0 weight per cent of Si, 1.0-3.0 weight per cent of Cu, O.100.20 weight per cent of A], 0.01-0.30 weight per cent of Nb, 0.010.04 weight per cent of N, 0.05 050 weight per cent of Pb, 0.01-0.20 weight per cent of Cd, balance essentially iron. 

1. HIGH-STRENGTH, ATMOSPHERE CORROSION RESISTANT PLATE STEEL WELDABLE UNDER WHATERVER CONDITIONS, CONSISTING OF 0.03-0.15 WEIGHT PER CENT OF C, 0.50-1.50 WEIGHT PER CENT OF NI, 1.01.9 WEIGHT PER CENT OF MN, 0.05-1.0 WEIGHT PER CENT OF SI, 1.0-3.0 WEIGHT PER CENT OF CU, 0.10-0.20 WEIGHT PER CENT OF AL, 0.01-0.30 WEIGHT PER CENT OF NB, 0.01-0.04 WEIGHT PER CENT OF N, 0.05-0.50 WEIGHT PER CENT OF PB, 0.01-0.20 WEIGHT PER CENT OF CD, BALANCE ESSENTIALLY IRON. 